Bioinspired nitrogen-bridged diatomic iron catalysts as efficient dual-enzyme mimics for visual analysis of antioxidants

Dual-atom catalysts have recently been recognized as promising alternatives to natural metalloenzymes. Inspired by the complex polymetallic active centers of natural metalloenzymes, we demonstrate the feasibility of the nitrogen-bridged diatomic iron catalysts (Fe2-N6-C) as highly efficient dual-enzyme mimics. It is noted that the as-prepared Fe2-N6-C catalysts show much higher activity than the single-atom iron catalysts (Fe1-N4-C). Experimental characterizations and theoretical simulations reveal that the N-bridged FeFe sites with an appropriate distance exert a synergy to enable more optimal intermediates adsorption and desorption, thus realizing enhanced dual-enzymatic performance. Taking advantage of the intrinsic dual-enzyme mimic activity of Fe2-N6-C catalysts, an innovative two-channel visual sensor array is constructed to distinguish and detect five common antioxidants. The sensor array can successfully identify 20 blind samples with a success rate of 100%. Moreover, a portable smartphone-based visual sensor assay is proposed, which could achieve on-site detection and differentiation of antioxidants based on their distinct color change. The present study illustrates the great potential of dual-atom catalyst-based sensor arrays as a promising visual platform for sensing applications.